Shutter devices of this kind are already known and are used principally for ventilators; one type is described e.g. in U.S. Pat. No. 3,960,464. The object of such shutter devices with ventilators is on the one hand to regulate, as required, the effect of the ventilator without having to regulate the ventilator motor itself, and on the other hand to prevent a so-called thermal fall when the ventilator is stopped; the shutter device shall then automatically close to prevent cold air from flowing into the space being ventilated.